As described in U.S. Pat. Nos. 5,591,444, 5,660,850, 5,665,372, and 5,858,390, cosmetic and aesthetic defects in the skin of a subject can be corrected by the injection of a suspension of autologous dermal fibroblasts into the dermis and subcutaneous tissue subadjacent to the defect. Typical defects that can be corrected by this method include rhytids, stretch marks, depressed scars, cutaneous depressions of non-traumatic origin, scaring from acne vulgaris, and hypoplasia of the lip. The cells are histocompatible with the subject, preferably derived by culture of a biopsy specimen taken from the subject, and have been expanded by passage in a cell culture system.
The injection of a material (an “injectate”) into the body, and particularly into the face, to create an aesthetic result dates to the close of the nineteenth century. For example, the injection of paraffin to correct facial contour defects enjoyed a brief period of acceptance in the years prior to World War I. However, complications and the unsatisfactory nature of the long-term results caused the practice to be abandoned. The availability of injectable silicone gave rise to a virtual repetition of these events beginning in the early 1960s. Specially manufactured “medical grade” silicone solutions, e.g., Dow Corning MDX 4.4011, have been used on an experimental basis in a number of approved test centers in the United States. Complications, such as local and systemic reactions to the silicone, migration of the injectate, and local tissue break down, have limited the use of silicone injections. The poor results obtained by the injection of non-biological materials prompted attempts to use foreign proteins, particularly bovine collagen, as an injectate. Although unprocessed bovine collagen is too immunogenic for injection into humans, the removal by enzymatic degradation of C- and N-terminal peptides of bovine collagen yields a material (“atelocollagen”) that can be used in limited quantities if patients are pre-screened to exclude those patients who are immunoreactive. Although used widely, the material was associated with the development of anti-bovine antibodies in about 90% of subjects and with overt immunologic complications in about 1-3% of subjects. DeLustro, F., et al., 1987, Plastic and Reconstructive Surgery 79:581. Atelocollagen in solution proved to be less than completely satisfactory because the material was absorbed in a relatively short time by the subject from the site of injection without replacement by host material. Residence in the body was increased by glutaraldehyde cross-linking, followed by filtration and shearing by passage through fine mesh. The increased and irregular viscosity rendered the material too difficult to use, however. Human collagen for injection that is derived entirely from a sample of the subjects own tissue is available but there is no evidence that human collagen injections are any more persistent than bovine collagen injections.
These problems were overcome through the development of the autologous fibroblast preparations. However, having a solution to a problem is not the same as having a product which is stable to store in defined dosages that have been validated by trial and error and confirmed by clinical trials, and which have been manufactured and packaged in compliance with the requirements of the U.S. Food and Drug Administration.
It is therefore an object of the present invention to provide defined dosage unit formulations of autologous dermal fibroblasts for injection into patients for the repair and long term augmentation of skin defects.
It is a further object of the present invention to provide dosage unit formulation that contain stem cells, precursor cells or partially differentiated cells that can be used for the repair and long term augmentation of skin defects.